The invention relates to a self-locking seatbelt retractor with a blocking element that can be triggered in a belt-sensitive and/or vehicle-sensitive manner for blocking the rotation of the belt shaft in the unwinding direction and with a tensioning drive that acts upon the belt shaft and that, upon triggering, rotates the belt shaft in the wind up direction of the security belt.
A seatbelt retractor with the state of the art features is described in DE 196 09 524 A1. In this connection, a tensioning drive is configured as a pyrotechnic cable tensioner that, upon triggering, sets a drive plate into rotation. The drive plate is connectable with the belt shaft via a centrifugal force coupling in the form of a radially outwardly displaceable rotation acceleration tensioner, so that the rotational movement of the drive plate in the belt wind up direction is transmitted over to the belt shaft.
To the extent that there occurs, at the conclusion of the tensioning process, a rotation of the belt shaft in the extension direction by reason of the commencing advance shifting of the belted-in passenger, which rotation is to be prevented by the belt retractor-side blocking element, this known configuration has the disadvantage associated therewith that a certain rotational path of the belt shaft in the belt wind up direction is required for a steering in of the blocking element after the conclusion of the tensioning movement before the blocking element is controlled into position and the further withdrawal of the seatbelt is blocked. Additional disadvantages to be noted include the factor that the configuration of an appropriate coupling between the belt shaft and the tensioning drive is expensive and, finally, the arrangement of the tensioning drive on the housing of the belt retractor and their fixed connection with one another brings with it a corresponding requirement for space to accommodate this arrangement.
The invention solves the challenge, with respect to a self-locking seatbelt of the above-noted art, of shortening, in particular for the blocking of the belt shaft following the conclusion of the tensioning movement, the requisite turn around path that exists until the engagement of the blocking element and, also, solves the challenge of reducing the size of the belt retractor-belt tensioner-combination.